So, my kids phone. I need her to be able to reboot the phone and access her account without going through primary account. How can this be done (without rooting). I don't want her be left without call access if her phone reboots or battery runs out.

Why I had to set her as secondary user is that as primary user she was able to circumvent parental control restrictions by creating and switching to guest account before parental control could prevent it. She figured that the lag works for her benefit because she can buffer commands by clicking icons where they will appear while the phone still lags behind.